1. Field of Invention
The current invention relates to methods of producing spatially patterned structures, and more particularly to methods of producing spatially patterned structures using fluorinated compounds. The current invention also relates to structures produced according to the methods. The current invention also relates to thin-film, lateral, organic heterojunction diodes.
2. Discussion of Related Art
Traditional photolithographic patterning has not proven useful to pattern organic semiconductors, and organic materials in general, because of damage by the photoresist, developer and acetone during the processing (Patterning Surfaces with Functional Polymers, Zhihong Nie and Eugenia Kumacheva, Nature materials, vol. 7, (April 2008)). Several approaches have been used to pattern organic semiconductors ranging from (a) use of parylene as a protective layer (Patterning Pentacene Organic Thin Film Transistors, Kymissis et al, J. Vac. Sci. Technol. B 20.3., (2002)), (b) use of parylene as mechanical resist (Photolithographic Patterning of Organic Electronic Materials, DeFranco et al, Organic Electronics 7 (2006) 22-28) and (c) use of UV curable precursors to pentacene (Flexible active-matrix displays and shift registers based on solution-processed organic transistors, Gelinck et al, Nature Materials, Vol 3, (2004)). The approach (a) can only be used to make bottom contact circuits and devices which have an order of magnitude lower performance. The approach (b), in addition to having the problems of approach (a), also has a problem of damage to the underlying parylene layer during mechanical peel off of parylene. The approach (c) is limited to only pentacene and has problems of lower mobility.
In addition, organic heterojunctions have been an extensive area of research for more than two decades and have found successful applications in Organic Light Emitting Diodes (OLEDs), and organic photovoltaics. While OLEDs are already on the market in display applications and are poised to enter the solid state lighting market in the near future, solar cells based on organic heterojunctions still need to achieve higher efficiencies to be commercially viable. With the advent of solar cells and OLED devices with increasingly complex device configurations and morphologies, it has become difficult to isolate and understand the various physical processes occurring at different interfaces and in the bulk at applied bias and in the presence of light. While devices based on organic heterojunctions have achieved significant technological milestones, the science behind them is still not completely understood and new techniques are needed to study the physics of such diodes
Because of the “buried” nature of interfaces in vertical or bulk heterojunctions, there has been little attempt to study properties, such as conductivity, dielectric constant, and morphology, on both sides of such interfaces in one device.
Therefore, there remains a need for improved methods of producing spatially patterned structures and structures produced according to the improved methods.